R Programming By Example

Interpreted dynamic typings

The second most important bottleneck people find is R's nature of being an interpreted and dynamically-typed language. This means that at any given line in your program, an object may be an integer, in the next line it may be a data frame, then a string, and it may be a list of data frames two lines later. This is the nature of not having fixed types for your objects, and since the interpreter can't know how to handle such objects in advance because they may be entirely different each time, it must check the object's type every time it wants to apply some kind of operation on it. This is a little exaggerated, but the point remains that since it's possible that an object's type changed, it must be continuously checked. ...